Insulating-tube for electric wires



, (No Model.)

' H. 'B. COBB.

INSULATING TUBE FOR ELECTRIC WIRES. No. 330,873. Patented Nov. 24, 1885.

Java E07? Qwp UNTTED STATES PATnNT @rrren.

HENRY COBB, OF WILMINGTON, DELAWVARE.

INSULATING-TUBE FOR ELECTRIC WiRES.

SPECIFICATION forming part of Letters Patent No.330,8'73, dated November2%, 1885.

Application filed February 14, 1885. Serial No. 155,887. (No model.)

To all whom it may concern.-

Be it known that I, HENRY B. COBB, a citizen of the United States,residing at Wilmington, in the county of Newcastle and State ofDelaware, have invented certain new and useful Improvements inInsulating Tubes for Electric Wires; and I hereby declare the fol lowingto be a full, clear, and exact description of the same.

My present invention is in the nature of an improvement for use in theapplication of the improvement in a system of laying subterranean linesof electric wires, for which Letters Patent of the United States, No.288,310, were granted to me November 13, 1883.

The object of the invention set forth in my aforesaid patent is statedtherein to be to dispense with metallic tubes, which incloseinsulating-tubes, as described in Letters Patent of the United States, N0. 288,311, granted to me November 13, 1883, for a new and improvedsystem of laying subterranean lines of electric wires by providing theinsulating tubes, through which separate wires are passed, with a closeand permanent coating of metal.

To practice the system involving the improvements described and claimedin my patent first herein referred to, it becomes necessary to providegreat lengths of the insulatingtubing for the incasement of electricwire, which is accomplished by uniting sections together until thedesired length of tubing is produced.

Wherever sections of insulating-tube have heretofore been coated withmetal and joined together, the metal coating has terminated at each endof the joint, as represented in my former patents referred to. To effectproper junction of these sections, whereby the joints connecting themshall be impervious to air and moisture, and whereby at the same time.clumsiness in their construction may be avoided, are,particularly thefirst-named,all-important requirements, since, unless the inclosed wireis completely insulated, in the sense that complete insulation isunderstood to mean in the art, the system to which the present inventionrelates, as aforesaid, is rendered defective; and to construct jointssufficiently impervious has always been found a matter of greatdifficulty. This difficulty is completely overcome by my presentinvention, which consists, broadly, in uniting the sections by asuitable joint, and providing the exterior With' a coating of metalextending from section to section over the joint.

My invention consists, further, in the preferred construction of thejoint shown in the first two figures of the accompanying drawings, inwhich Figure 1 is a longitudinal section of two broken sections oftubing formed of insulating material, one having inserted into one end ashort metallic connecting tube and constructed to form the male portionof a joint, while the other is constructed to afford,toward its endadjacent to the male portion of the joint upon the first-named sectionto receive the latter, a female portion narrower in diameter than themale portion and through which the short connecting-tube is insertedinto the adjacent section of insulating-tubing; and Fig. 2 is a similarView representing the parts shown in Fig. 1 joined together by shrinkingthe female portion of the joint upon the male portion and having theexterior surfaces of the insulatingtubing and the line of their junctioncoated over with a continuous close covering of metal and incasing anelectric Wire. Fig. 3 of the drawings represents, in longitudinalsection, a modified construction for the joint, which illustrates mybroad invention in perhaps its simplest practicable form.

A and A are broken sections of tubing composed of insulating material,preferably in the form of hard rubber. As shown, the part A is reducedtoward one extremity to provide the shoulder t, preferably beveled, asshown, and the bevel s at its extreme end. The part A is formed towardits extremity adjacent to that of the section A just described, tocoincide internally with the shape of the reduced portion of the part Aand receive the latter, affording to it a close fit by making the femaleportion narrower in diameter than the part which enters it, and heatingthe part A to eX- pand it, and thereby permit the insertion into it ofthe male portion and allowing it to shrink thereon by cooling. Theopposite extremity of each section A is formed like the extremitydescribed of the section A, and that of each section A corresponds inconstruction with the described extremity of the section A.

' tube B to be received into and lit snugly withsorb moisture.

in them in joining them together and abut at each extremity, when thesections are adjusted together, against shoulders r provided in thedrilling out, whereby the inner surface of the connecting-tube shall beflush with that of the insulating-tubes, and the edges thus afford noobstruction in introducing the wire.

The incasement of the electric wire 0 is preferably accomplished bystringing the-sections of insulating-tubing and connecting-tube upon itand adjustingthe parts together in the manner described previously, ifdesired, coat ing the exteriors of the male portion of the joint andprojecting portion of the connectingtube with asuitable cement that willnot ab- Vhen a length of tubing not too great to permit readymanipulation shall have been thus formed, a close metallic coating, D,is provided, preferably by electrodeposition, to extend over theexternal surface afforded by the connected sections of tubing and thelines of their junction. The essential features of this joint are theinterior tube, B, and the exterior metalliccoating, D,which, it will beseen, would prove effective, even if the ends of the sections ofinsulatingtubes were not inserted one within the other, but simply met.The construction represented in the drawings, however, is the onepreferred The modification represented in the third figure of thedrawings shows a way, by far sim' pler than the one hereinbeforedescribed, of joining sections of the insulating-tubing, by omitting theconnecting-tube B, one end of section A being externally beveled and thecoated, if desired, with a suitable cement, and the adjacent end of thesection A being internally beveled to receive the latter and producethereof a snug fit, and coating with metal from section to section overthejoint, all in the manner hereinbefore described. This construction,however, owing mainly to the omission of the comiecting-tube B, does notgive the strength afforded by the construction of joint hereinbeforereferred to as that constituting the preferred construction, and istherefore not so desirable as the latter. The-two constructions,however, are generic, owing to the fact that sections are joinedtogether and provided with a coating of metal continued over the joint,and the same would be true whatever of many possible forms of jointmight be employed, provided the metal covering be continued over it.

\Vhat I claim as new, and desire to secure by Letters Patent, is

1. Sections of insulating-tubing connected together at their ends and,provided with a close and permanent covering of metal formed upontheexteriors of the sections of tubing and continued from section tosection over the joints, substantially as described.

2. In combination with sections ofinsulatingtubing fitting one withintheother at their ends, an internal tube, B, of tenacious materialextending into both tubes, having its inner surface flush with the innersurface of the tubes which it enters, substantially as described.

3. In combination with sections ofinsulatingtubing fitted. together attheir ends, an inter nal tube, B, of tenaceous material extending intoboth tubes, and aclose covering of metal upon the exterior of the unitedsections and extending from one section to another over the joint,substantially as described.

4. In combination with sections ofinsulatingtube A and A,'inscrted oneinto the other at their ends, an internal connectingtube, B, oftenacious n'iaterial entering both sections, and a close and permanentcovering of metal upon the exterior of the sections continued over thejoint from one section to another, substantially as described.

HENRY E. 001313. In presence of WM. H. DYnnNFoRTH, A. L. STANFORD.

